Patent GB-1020959-A (GB)
Title: Improvements in electric analog computers
IPC: G06G7/122
Filed: 1964-02-27
Abstract: 1,020,959. Electric analogue calculating. CSF COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL and SOC. MARCAINE DE RECHERCHES D'ETUDES ET DE DEVELOPPEMENTS "SOMAREDE." Feb. 27, 1964 [Feb. 27, 1963], No. 8304/64. Heading G4G. An analogue computer for finding maxima or minima of a function F(x 1  ... x q ) when the variables are subject to p conditions uses these p equations together with q further equations when the coefficients # are Euler-Lagrange multipliers. In Fig. 1 a known computer C is provided with inputs x 1  - x q  and supplies outputs f 1 -f p  at terminals S 1 -S p , outputs #ft/#xj at terminals S ij,  and outputs #f1/#x1 - f#/#xq   at terminals T 1 -Tq. The switcher unit R may comprise a matrix arrangement, Fig. 2 (not shown), and receives inputs from terminals S and T and also receives inputs corresponding to # 1 -# p  from generators 2 1 -2 p  and a constant input K from generator 3. The unit R multiplies and adds its inputs to form the q quantities These outputs # are fed to generators 1 1 -1 q  which supply the inputs to computer C. The generators alter their output voltages in a direction determined by the sign or phase of the input ( according to whether the system uses D.C. or A.C.) as long as the input is not zero. Similar generators 2 1 -2 p  receive inputs f 1 -f p  from C and supply outputs X to R. At equilibrium the inputs to all the generators are zero and so the required conditions are satisfied. The variation of K may be limited to a change of sign, to select a maximum or a minimum, or it may also change in magnitude. The generators 1 and 2 may comprise a servomotor the shaft of which controls a network supplied with unit input voltage; the input voltage to the servomotor controls the position of the shaft and thus the output voltage of the network, Fig. 3 (not shown). Alternatively the generator may comprise the parallel combination of an integrator and an amplifier so that an input u produces an output a u + b # u dt, where a and b are constants, Fig. 4 (not shown). For stability the two sets of generators are preferably of different types. Calculating minimum of x<SP>2</SP> + y<SP>2</SP> when ax + by + c = 0.-In Fig. 6 an amplifier A 1  governs a servo G which causes three voltage-to-current or current-to-voltage transformers to multiply their inputs by a quantity x as a function of the angular position of the output shaft of the servo. With unit input to transformer C, its output is x and is fed to unit ax where it is multiplied by a. Similarly unit b y provides b y, and ax is added to b y and c and fed to the generator 2 1  which provides an output #. # is multiplied by a and b in units ax and b y and fed to the inputs of A 1  and A 2 . Unit X<SP>2</SP> receives X<SP>2</SP> from transformer C<SP>1</SP> and this is added to y<SP>2</SP> in unit 30 1  to provide an output x<SP>2</SP> + y<SP>2</SP>. Unit 30 also supplies a constant K to reversible voltage-to-current transformer 2 in units x<SP>2</SP> and y<SP>2</SP>, which produce outputs 2K; these are multiplied by x and y respectively in SM1 and SM2 and fed to the inputs of A 1  and A 2 . When the system is in equilibrium the input to 2 1  is zero, so ax + by + c = 0. Also the input to A 1  is zero so 2Kx + #a = 0, the first Euler- Lagrange equation; similarly the second Euler-Lagrange equation is also satisfied at the input to A 2 .